Studies concerning the structure and function of the renal lymphatic system are proposed. Special attention will be paid to the formation of renal lymph as revealed by morphological studies of renal lymphatic endothelium under control and experimental conditions. Radioactive albumin will be used as a tracer to delineate translymphatic pathways by autoradiography. Quantitative data will be obtained by stereologic morphometric methods. The effects of changes in plasma protein concentrations upon morphologically visible lymphatic transport routes will also be subjected to qualitative and quantitative analysis. Morphometric data obtained from these studies will be correlated with estimates of lymphatic capillary permeability, as measured in volume per unit time per unit square area, in order to define any specific relationships. Studies on measurements of renin concentrations in renal lymph and plasma will be expanded to include measurement of prostaglandin E2 and prostaglandin F2a. Interstitial relation to changes in renal blood flow during control and experimental conditions in dogs. These experiments will provide information on the intrarenal control of renal blood flow.